Brajković Josip, Pezer Željka, Bruvo-Mađarić Branka, Sermek Antonio, Feliciello Isidoro, Ugarković Đurđica
Department of Molecular Biology, Ruđer Bošković Institute, HR-10000 Zagreb, Croatia.
Department of Molecular Biology, Ruđer Bošković Institute, HR-10000 Zagreb, Croatia
G3 (Bethesda). 2018 Mar 2;8(3):875-886. doi: 10.1534/g3.117.300267.
Satellite DNAs are tandemly repeated sequences clustered within heterochromatin. However, in some cases, such as the major TCAST1 satellite DNA from the beetle , they are found partially dispersed within euchromatin. Such organization together with transcriptional activity enables TCAST1 to modulate the activity of neighboring genes. In order to explore if other repetitive families have features that could provide them with a possible gene-modulatory role, we compare here the structure, organization, dispersion profiles, and transcription activity of 10 distinct TCAST repetitive families including TCAST1. The genome organization of TCAST families exhibit either satellite-like or transposon-like characteristics. In addition to heterochromatin localization, bioinformatic searches of the assembled genome have revealed dispersion of all families within euchromatin, preferentially in the form of single repeats. Dispersed TCAST repeats are mutually correlated in distribution and are grouped in distinct regions of euchromatin. The repeats are associated with genes, are enriched in introns relative to intergenic regions, and very rarely overlap exons. In spite of the different mechanisms of repeat proliferation, such as transposition and homologous recombination, all TCAST families share a similar frequency of spreading as well as dispersion and gene association profiles. Additionally, TCAST families are transcribed and their transcription is significantly activated by heat stress. A possibility that such common features of TCAST families might be related to their potential gene-modulatory role is discussed.
卫星DNA是串联重复序列，聚集在异染色质内。然而，在某些情况下，例如来自甲虫的主要TCAST1卫星DNA，它们部分分散在常染色质中。这种组织方式与转录活性一起使TCAST1能够调节邻近基因的活性。为了探究其他重复家族是否具有可能赋予它们基因调节作用的特征，我们在此比较了包括TCAST1在内的10个不同的TCAST重复家族的结构、组织、分散图谱和转录活性。TCAST家族的基因组组织呈现出卫星样或转座子样特征。除了异染色质定位外，对组装基因组的生物信息学搜索还揭示了所有家族在常染色质内的分散情况，优先以单拷贝重复的形式存在。分散的TCAST重复序列在分布上相互关联，并聚集在常染色质的不同区域。这些重复序列与基因相关，相对于基因间区域在内含子中富集，并且很少与外显子重叠。尽管重复序列增殖的机制不同，如转座和同源重组，但所有TCAST家族都具有相似的扩散频率以及分散和基因关联图谱。此外，TCAST家族被转录，并且它们的转录在热应激下显著激活。本文讨论了TCAST家族的这些共同特征可能与其潜在的基因调节作用相关的可能性。
